Flying three times successfully was among the criteria the company needed to meet to become eligible to compete for military business under a new program designed to draw competition into a field now monopolized by United Launch Alliance, a partnership of Boeing and Lockheed Martin.

"The new entrant criteria did say three launches are required (for Falcon 9) before certification can happen for national security payloads," said SpaceX Communications Director Kirstin Brost Grantham.

There are several paths toward certification, and the requirements can vary, Air Force spokeswoman Tracy Bunko said.

The recently launched Spacex Falcon 9 and the upgraded version that should fly later this year.

The Air Force is expected to award a non-ULA launch services contract this year for the Deep Space Climate Observatory, a NASA Earth-monitoring satellite that is being repurposed by the National Oceanic and Atmospheric Administration (NOAA) into a solar observatory. The Air Force issued a request for bids on May 11.

A second satellite, the Air Force's Space Test Payload-2, also has been set aside for a new launch services provider.

Last week, SpaceX added Intelsat as the first customer for its planned Falcon Heavy rocket, which is expected to have twice the lift capacity of ULA's Delta 4 Heavy, currently the biggest booster in the U.S. fleet.

A Falcon Heavy mission costs between $83 million and $128 million, according to SpaceX's website, a fraction of a Delta 4 Heavy rocket launch.

For now, ULA isn't worried.

"In order for a fair competition, a new entrant would need to support the full set of mission and technical requirements. In addition, entrants also will be faced with stringent government oversight, accounting and reporting requirements - none of which is part of a commercial business plan," ULA spokeswoman Jessica Rye wrote in an email to Reuters.